Study of applied electrical field effect on semiconductor crystall growth mechanism from melt and crystal growth for x-ray detectors

对液相电外延生长晶体进行了数值模拟和实验研究。采用控制体积法描述连续性、N-S方程、能量方程和考虑电迁移的传质方程，并用SIMPLE技术进行求解。数值结果表明，在系统温度保持不变的情况下，由于电场作用引起的Peltie效应降低了衬底温度，而温度分布则引起了自然对流。为了抑制自然对流，施加磁场是有益的。然而，在强磁场下可以观察到空穴。因此，研究了旋转对液体对流的抑制作用与磁场对液体对流的影响。旋转引起的Coliori力抑制了液体中的对流，而生长界面附近的浓度梯度必须是陡峭的，因为高密度的物质会被离心力除去。实验结果表明，Si、GaAs衬底与液体发生了化学反应，因此需要在衬底中加入CdTe作为衬底。在此衬底上成功生长出厚度为23μm的Cd Te晶体。研究了生长温度对晶体质量的影响。

Crystal growth by Liquid Phase Electroepitaxy was studied numerically and experimentally. Continuity, Navier-Stokes, Energy equations and Mass transfer equation considering electro-migration were descritized by control volume method and solved by SIMPLE technique. Numerical results show that substrate temperature is decreased by Peltie effect caused by electric application and natural convection is caused by the temperature distribution even if the system temperature was kept constant. In order to suppress the natural convection, magnetic field application is beneficial. However, holes are observed under strong magnetic fields. Therefore, effect of rotation, which has similar effect on suppression of convection to the magnetic field, on the liquid convection was investigated. Convection in the liquid was suppressed by Coliori force caused by rotation and concentration gradient near the growth interface must be steep because high density materials will be removed by centrifugal force. As the results, it can be expected that crystal growth rate becomes higher by applying rotation.In the experiments, it was shown that Si, GaAs substrates reacted with liquid and it was concluded that CdTe substrate is required. CdTe crystal with 23 μm thickness was successfully grown on the CdTe substrate. Effect of growth temperature on the crystal quality was also investigated.